1. Field of the Invention
The present invention relates to a ball grid array type of semiconductor device, and more particularly, to a ball grid array type of semiconductor device in which solder balls are directly connected to a metal lead frame which is used in a plastic package.
2. Description of Related Art
Recently, semiconductor devices have been used in various application fields such as the industrial appliance field and consumer appliance field as integration has increased.
One package type semiconductor device is a ball grid type of semiconductor device. This type of semiconductor device is disclosed in, for example, U.S. Pat. No. 5,216,278. FIG. 1 shows a cross sectional view of the semiconductor package. Referring to FIG. 1, a semiconductor chip 101 having a plurality of electrode pads 102 is mounted on a substrate 111 made of, for example, epoxy resin with a silver paste. A plurality of wiring layer patterns 113 formed of copper foil with a predetermined pitch are provided around the semiconductor chip 101 on the front and rear surfaces of the substrate 111. The one end of the wiring layer pattern 113 on the front surface side is provided with an electrode pad 112 which is connected to the corresponding electrode pad 102 on the semiconductor chip 101 by a wire 103. The other end of the wiring layer pattern 113 on the front surface side is connected to the wiring layer pattern 113 on the rear surface side Via a through-hole 116. All the components mentioned above are sealed by resin on the front side of the substrate 111. A solder ball 106 is adhered to a solder pad 114 on the wiring layer pattern 113 on the rear surface side by a reflow process.
A method of manufacturing this conventional ball grid array type of semiconductor device will be described below. First, the semiconductor chip 101 is adhered to the resin substrate 111 made of glass epoxy resin by adhesive such as a silver paste. Then, the electrode pads 102 of the semiconductor chip 101 and the corresponding electrode pads 112 of the substrate 111 are connected by the wires 103 through bonding connection, respectively.
Next, a solder mask 115 is provided on the rear surface of the resin substrate 111 and solder balls 116 are melted and connected to solder pads 114 through openings located at predetermined positions. The solder ball 106 and the electrode pad 102 on the semiconductor chip 101 are connected via the solder pad 114, the wiring layer pattern 113 on the rear side, the through-hole 116, the electrode pad 112 on the wiring layer pattern 113 of the front side, and the wire 103.
In this manner, in the conventional ball grid array type of semiconductor device, there are required the space for the electrode pad 112 and through-hole 116, and the wiring layer pattern 113 on the substrate 111 around the semiconductor chip 101 and the steps for forming them. For this reason, manufacturing costs for this conventional type of ball grid array semiconductor device including material cost, process cost, and assembly cost is increased.